Structural Identification of &lt;i&gt;Lentinus edodes&lt;/i&gt; Cellulose Derivative that Inhibits Aflatoxin Production by &lt;i&gt;Aspergillus flavus&lt;/i&gt;

H-B Li,L-B Hu,H-Z Mo,M-Y Wang,D-D Pan

doi:10.4314/tjpr.v14i3.19

Abstract

Purpose: To identify the structures of cellulose-extract derivative (CED) formed by heating Lentinus edodes cellulose in water surroundings that can efficiently inhibit aflatoxin production by Aspergillus flavus.Methods: CED was purified on Sepharose CL-6B columns, and then structurally characterized using amino acid analyzer, gas chromatography, Fourier transform infrared spectroscopy, and polyacrylamide gel electrophoresis.Results: CED completely inhibited aflatoxin AFB1 production by A. flavus at concentrations ≥ 100 μg/ mL. Chemical analysis indicated that CED contained 82 % carbohydrate and 18 % protein and has a molecular weight of approximately 24 kDa. Monosaccharide component analysis indicates that glucose was the predominant monosaccharide of CED. Analysis by Smith degradation and enzymatic hydrolysis indicate that there were only (1, 4)-glycosidic linkages in the CED polysaccharide chains. The protein backbone of CED contained 15 kinds of amino acid with higher levels of glutamic acid, aspartic acid, leucine and alanine.Conclusion: CED was identified as a complex of peptide and polysaccharide structures possessing β- (1, 4)-glucan backbones, and it provides a theoretical basis for developing polysaccharide preparations to control aflatoxin contamination with medical and food science applications.Keywords: Aflatoxin B1, Lentinus edodes, Aspergillus flavus, Cellulose derivative, Structure identification, Amino acid

Highlights

Aspergillus flavus occurs as a saprophyte in soils worldwide and causes diseases in several important crops, such as maize, peanut, and cottonseed, before and after harvest [1]
The greater concern is that A. flavus can produce aflatoxin B1 (AFB1), which has been implicated as a causal agent of liver cancer in humans and other animals [2]
Further analysis showed that cellulose-extract derivative (CED) concentration-dependently inhibited AFB1 production by A. flavus, with an IC50 of < 10 μg/mL

Summary

INTRODUCTION

Aspergillus flavus occurs as a saprophyte in soils worldwide and causes diseases in several important crops, such as maize, peanut, and cottonseed, before and after harvest [1]. We discovered that hot waterseparated cellulose-extract derivative (CED) from L. edodes fruiting bodies can efficiently inhibit aflatoxin production by A. flavus. Sabouraud's medium (peptone 1 g, glucose 4 g, water 100 mL) was used to culture A. flavus for aflatoxin production. The precipitate was washed with distilled water several times through Whatman No. filter paper and the dried cellulose was used for CED production. Ten grams of powdered cellulose extract were re-suspended in 100 mL of distilled water for 15 min at 125 °C, and filtered through Whatman no. Total CED carbohydrate content was determined by the phenol-sulfuric acid colorimetric method using glucose as the standard. The reaction mixture was dialyzed in moving tapwater (24 h) and distilled water (24 h), and the retained material was concentrated and reduced with NaBH4, neutralized with 50 % acetic acid, and dialyzed. P < 0.05 was considered to be indicative of statistically significant difference

RESULTS

DISCUSSION

CONCLUSION